1.1.1.3 additional information NADP does not act as a cofactor for this enzyme, but as a strong inhibitor of NAD+-dependent oxidation of Hse, analysis of the cofactor-binding site of the enzyme, Pyrococcus horikoshii HseDH shows a unique cofactor binding mode, which is not observed in conventional NAD(P)-dependent dehydrogenases. Superposition of the Hse/NADPH-bound K57A structure onto the NADPH-bound wild-type structure shows that the NADPH molecule in the mutant structure is positioned/configured nearly identically to the NADPH molecule in the wild-type structure, except for the positioning of the C2 phosphate group of the adenine ribose. The C2 phosphate is tightly held in position through five surrounding hydrogen bonds in the wild-type enzyme. In K57A mutant the C2 phosphate group is rotates in a clockwise direction around C2B of NADPH by about 30° relative to the wild-type structure. The guanidino group of Arg40 in the mutant is also rotated clockwise by about 90° around the NE atom of Arg40 relative to the wild-type structure 741408 1.1.1.3 NAD+ - 739972, 741408, 760354, 760402, 761404, 761712, 762359 1.1.1.3 NAD+ binding structure analysis, overview 762453 1.1.1.3 NAD+ low activity 246392 1.1.1.3 NADH - 246382, 246396, 654955, 739972, 741408, 760354, 760402, 761404, 761712, 762359, 762453 1.1.1.3 NADH GmHSD displays a 1.6fold preference for NADPH over NADH as the cofactor in the oxidation reaction. In the reduction reaction NADP+ is favored nearly 4fold as the cofactor 712490 1.1.1.3 NADH threonine sensitive isozyme can use NADPH or NADH, threonine insensitive isozyme can use NADPH only 246388 1.1.1.3 NADP+ - 246387, 246391, 657018, 688167, 738802, 739791, 739804, 739972, 740548, 740860, 760736, 761404, 762359 1.1.1.3 NADP+ enzyme BsHSD exclusively prefers NADP+ to NAD+ 761687 1.1.1.3 NADP+ no activity of the wild-type enzyme with NADP+, but only with enzyme mutants R40A and K57A 741408 1.1.1.3 NADP+ preferred 246392 1.1.1.3 NADP+ StHSD also exhibits activity with NADP+, but with much lower efficiency compared to NAD+ 762453 1.1.1.3 NADPH - 246385, 246387, 246391, 246396, 654955, 657018, 670165, 688167, 738802, 739791, 739804, 739972, 740548, 740860, 760736, 761404, 761687, 762359, 762453 1.1.1.3 NADPH GmHSD displays a 1.6fold preference for NADPH over NADH as the cofactor in the oxidation reaction. In the reduction reaction NADP+ is favored nearly 4fold as the cofactor 712490 1.1.1.3 NADPH no activity of the wild-type enzyme with NADPH, but only with enzyme mutants R40A and K57A 741408 1.1.1.3 NADPH preferred 246382 1.1.1.3 NADPH threonine sensitive isozyme can use NADPH or NADH, threonine insensitive isozyme can use NADPH only 246388